The present invention relates to a mat supported jack-up platform that can be used for drilling and production operations offshore.
Offshore drilling operations are often conducted using bottom-supported platforms or rigs. One of the most common types of bottom-supported rigs are jack-up rigs that have legs that can be jacked up and down in relation to the platform hull by rack-and-pinion systems. Conventional rigs are towed to a location of prospective drilling operations, while the legs are elevated above the platform, or hull. Once the rig reaches the pre-determined location, the legs are lowered to the bottom and the platform is “jacked up” above the expected wave action to a desired operational draft. The legs are embedded into the sea bottom to support the elevated platform. Some of the rigs have spud cans secured to the bottom of the legs for resting on the sea floor.
Another type of jack-up rigs uses a mat that is secured to the bottom of the legs. Such rigs are often employed for muddy, soft bottom conditions. A conventional mat-supported jack-up rig has a base mat, which is a rectangular hollow tank sized to provide stability for the rig when resting on the seafloor.
The interior of a typical mat is divided into ballast compartments, which can be flooded to make the mat neutrally buoyant, while the platform is being towed to the drilling site. When a mat supported jack-up is conducting drilling operations, the mat is negatively buoyant and is positioned in contact with the sea floor. The mat distributes the weight of the rig evenly over the bottom and tends to keep it from sinking too far into a soft bottom.
The need for ballasting and de-ballasting of the mat structure requires that the rig be equipped with pumps and associated equipment, which increases the cost of the rig and associated drilling operations.
The present invention contemplates elimination of drawbacks associated with the prior art and provision of an improved mat-supported offshore platform, wherein the need for the pumping equipment is eliminated.